I was probably spoiled by the first CNC that I built - based on a Proxxon MF70, it worked it's little heart out to give almost unmeasurable errors, really smooth curves etc.. I would like to get a step resolution of 0.0025mm but would settle on 0.005mm. I am thinking of 2.5:1 (1000 half-steps per leadscrew revolution) with 16T to 40T Syncroflex 2.5mm pitch pulleys and 6mm wide belt - would that work with a 3Nm stepper motor?